|Publication number||US7594439 B2|
|Application number||US 11/518,846|
|Publication date||Sep 29, 2009|
|Filing date||Sep 11, 2006|
|Priority date||Sep 10, 2005|
|Also published as||DE102005043122A1, DE502006005719D1, EP1762841A1, EP1762841B1, US20070056373|
|Publication number||11518846, 518846, US 7594439 B2, US 7594439B2, US-B2-7594439, US7594439 B2, US7594439B2|
|Inventors||Eberhard Fischer, Rainer Meier, Friedrich Mohr|
|Original Assignee||Intelligendt Systems & Servises Gmbh|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (20), Non-Patent Citations (1), Referenced by (3), Classifications (18), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The invention relates to a method and device for the ultrasonic testing of a workpiece having an uneven surface.
It is particularly in the area of welded seams, that workpieces have an uneven surface at roots and cover pass which is normally ground by hand. In spite of such manual grinding, even surfaces are not reached in this process. When welding together pipes of rustproof steel, there is also strong drawing-in due to shrinkage during the cooling which causes additional unevennesses. Welded joints in pipeline systems of nuclear power stations also have starting threads at the inside diameter of pipes for adapting the inside diameter and transition slopes to the original diameter, platings on ferritic pipelines, buffer welds on the ferritic material for welding to austenitic components and transition slopes for diameter expansion on stubs. All this has the effect that the ultrasonic test sensors used for testing such a welded seam must be placed and moved on uneven irregularly wavy workpiece surfaces both in internal and external testing. An example of such an uneven or wavy surface of a workpiece is reproduced in
The gap 14 is filled with a coupling medium, as a rule water. Reflections in the gap 14 between coupling face 12 and surface 13 cause interferences which can weaken the ultrasonic signal by up to about 14 dB in the worst case. In addition, the ultrasonic beam is irregularly refracted at the wavinesses of the workpiece surface and the formation of a sonic beam is prevented. This can lead to defects (reflectors) in the workpiece 2 being overlooked.
In order to solve the problems associated with this unevenness or waviness, it was attempted to perform the testing from test positions at which the surface 13 of the workpiece 2 is even, i.e., in which the test head 10 is seated as flatly as possible on the surface 13. In other words: the test head 10 was placed on offset from the welded seam 6. However, such a possibility is not practicable for a large number of applications due to the boundary conditions explained above. As an alternative, test heads are also used which are narrow in a direction parallel to the waviness—perpendicularly to the plane of the drawing in the example of FIG. 1—so that they can follow the contour of the wave when the test head is moved over the welded seam so that a distinct, irregularly shaped coupling gap 14 as shown in
From the publication S. Mahaut et al., Pipe Inspection using UT Smart flexible Transducer, Technical Paper, 8th ECNDT Barcelona 2002, an ultrasonic test head is known, the coupling face of which is flexible and can adapt itself to the surface contour of the workpiece. To this end, the ultrasonic test head contains a multiplicity of transducer elements arranged in a row and mechanically separated from one another so that the array formed in this manner can adapt itself to the surface contour of the workpiece and has the same contour on its rear side. This rear contour is measured with an optical measuring arrangement. The individual transducer elements of the array are then driven with a delay time which is corrected in accordance with this contour in order to correctly adjust acoustic irradiation angle and depth of focus in this manner. However, the separate construction of the individual transducer elements with wearing layer, adaptation layer, piezoelectric oscillator, damping compound and electrical wiring and their mechanical suspension and water tightness is very expensive. In addition, such a test head only exhibits limited durability and ruggedness.
The invention is then based on the object of specifying a method for the ultrasonic testing of a workpiece having an uneven surface, which does not have the disadvantages mentioned above. In addition, the invention is based on the object of specifying a device operating in accordance with this method.
With respect to the method, the said object is achieved according to the invention by means of a method having the features of patent claim 1. In the method for the ultrasonic testing of a workpiece having an uneven surface with an ultrasonic test head, acoustically coupled to the workpiece, which contains a multiplicity of transducer elements arranged rigidly in a linear array, which can be driven in a time-delayed manner with a delay time predetermined for each transducer element, the propagation time of an ultrasonic signal transmitted by an individual transducer element and reflected from the surface and received by this transducer element is measured for a number of the transducer elements and is used for correcting the delay times, and the transducer elements are subsequently driven with these corrected delay times. Due to these measures, wavy workpiece surfaces can be tested with a simple and rugged construction of the ultrasonic test head.
If, in addition, an angle of inclination of the ultrasonic test head is measured with respect to a mean straight-line surface contour of the workpiece and is taken into consideration in determining the corrected delay times, inclined positions of the ultrasonic test head caused by a waviness of the surface of the workpiece can be detected and compensated for by correspondingly corrected drive of the transducer elements.
With regard to the device, the object according to the invention is achieved by means of a device having the features of patent claim 3, the advantages of which, like the advantages of its subordinate patent claims, correspond to the advantages specified in each case for the associated method claims.
For further explanation of the invention, reference is made to the exemplary embodiment of the drawing, in which:
The transducer elements 20 1 to 20 n are driven by a control and evaluating device 22 with a delay time t1 to tn predetermined for each transducer element 20 1 to 20 n in order to adjust in this manner the angle of acoustic irradiation β and the position of the focus F of an ultrasonic signal 21 coupled into the workpiece 2. In the example shown, there is a defect located in the area of the focus F which leads to an echo signal which is received by the transducer elements 20 1 to 20 n. Due to the known angle of acoustic irradiation β and the measured propagation time of the echo signal, the defect can be located in the workpiece 2.
The transducer elements 20 1 to 20 n are now driven successively in time by means of the control and evaluating device 22 in an operating mode in which they operate separately in each case in pulse-echo mode. In other words, first the transducer element 20 1 is driven and the ultrasonic waves transmitted by this transducer element 20 1 propagate towards the workpiece 2 with a large aperture angle. The ultrasonic waves are reflected at the surface 13 a of the workpiece 2 and generate an entry echo signal. The transducer element 20 1 essentially only receives those reflected ultrasonic waves as entry echo signal which impinge perpendicularly on the surface 13 a, i.e. at point Ra1. The propagation time of this entry echo signal, i.e. of the ultrasonic signal reflected from the surface 13 a and received by the transducer element 20 1 is measured and recalculated into a distance which in the present case is equal to the distance d between receiving and transmitting face 33 and surface 13 a. If the actual surface contour of the workpiece 2 in the test position is unknown, the point Ra1 of the surface of the workpiece 2 from which the received echo signals emanate could also be located on a circular arc 30 a 1 which is shown dot-dashed in the figure.
Following this, the transducer element 20 2 is driven and the propagation time of the echo signals received by the transducer element 20 2 is also measured. In this manner, each of the transducer elements 20 1 to 20 n is driven. In the figure, the situation for the transducer element 20 n−1 is also drawn for which the same conditions are obtained for the level surface 13 a as for the transducer element 20 1 (reflection of the entry echo signal in Ra(n−1)) which can be located on the circular arc 30 a n−1 if the contour is not known.
In the case of the level surface 13 a, the entry echo signal reaches each transducer element 20 1 to 20 n after the same propagation time which is needed for traveling twice the distance d between transmitting and receiving face 33 of the transducer elements 20 1 to 20 n and surface 13 a.
A situation is then drawn dashed which is obtained when a concavely curved surface 13 b is present. The figure shows that in this case the transducer element 20 1 receives an entry echo signal for an ultrasonic wave emitted perpendicularly to the transmitting face from point Rb1. However, assuming a lack of knowledge of the actual surface contour, here, too, the entry echo signals can come from points which are located on the circular arc 30 b 1. In the example shown, the transducer element 20 n−1 now receives the entry echo signal from a point Rb(n−1) of the surface 13 b which is not in the direction of the normal of the transducer element 20 n−1. Here, too, however, the entry echo signals can come from points which are located on the circular arc 30 b n−1.
The situation is different in
This information is then used for adapting the time delay for the individual transducer elements to the different shape of the coupling gap with the aid of the control and evaluating device 22 and for adjusting the correct angle of acoustic irradiation β with respect to the mean surface contour 16.
In this manner, the predetermined angle of acoustic irradiation β can be correctly adjusted even with a wavy surface 13 of the workpiece 2 as is shown in
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|U.S. Classification||73/626, 73/628, 73/634|
|International Classification||G01N29/26, G01N29/06|
|Cooperative Classification||G01N29/07, G01N29/262, G01N2291/106, G01N2291/2675, G01N2291/056, G01N29/30, G01N2291/044, G01N29/341, G01N2291/2638|
|European Classification||G01N29/26E, G01N29/34B, G01N29/30, G01N29/07|
|Mar 9, 2009||AS||Assignment|
Owner name: INTELLIGENDT SYSTEMS & SERVICES GMBH & CO. KG, GER
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:FISCHER, EBERHARD;MEIER, RAINER;MOHR, FRIEDRICH;REEL/FRAME:022364/0063
Effective date: 20061106
|Jul 27, 2009||AS||Assignment|
Owner name: INTELLIGENDT SYSTEMS & SERVICES GMBH, GERMANY
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:INTELLIGENDT SYSTEMS & SERVICES GMBH & CO. KG;REEL/FRAME:023007/0739
Effective date: 20050713
|Feb 10, 2010||AS||Assignment|
Owner name: INTELLIGENDT SYSTEMS & SERVICES GMBH,GERMANY
Free format text: CHANGE OF NAME;ASSIGNOR:INTELLIGENDT SYSTEMS & SERVICES GMBH & CO. KG;REEL/FRAME:023915/0588
Effective date: 20080924
|Mar 8, 2013||FPAY||Fee payment|
Year of fee payment: 4